Thermal conductivity of diamond and related materials from molecular dynamics simulations

The authors examine herein how to use molecular dynamics (MD) simulations to provide some understanding of the various process related to thermal conductivity and discuss the limitations in such approaches. They use of Green-Kubo relation derived from linear response theory to extract the thermal conductivity from energy current correlation functions. They find that the accuracy of thermal conductivity is sensitive to the size of the periodic unit cell in the MD simulation (which limits the phonon wavelength). However, they find that it is possible to extract an accurate thermal conductivity from periodic cells 60 times smaller than the actual phonon mean free path. The reason is that the energy current correlation time is much shorter than energy relaxation time. They illustrate this by using equilibrium MD simulations to calculate thermal conductivity of bulk crystalline diamond, including the effect on vacancies, isotopes, mass, and nanostructures.